radiation discovery wihelm conrad roentgen: 1985 x-ray: unknown nature discovered when...
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Radiation Discovery
Wihelm Conrad Roentgen: 1985X-ray: unknown natureDiscovered when experimenting with a
cathode ray tube 1st dental radiograph: 1896
Fundamental of Radiation Radiation
Emission & propagation of energy through space
Particulate RadiationTiny particle of matter that possess mass &
travel in straight lines at high speedsElectrons, beta particles, cathode rays,
protons, alpha particles, neutrons
Fundamental of Radiation Electromagnetic Radiation
Propagation of wave-like energy (w/out mass) through space or matter
X-rays, cosmic rays, UV rays, visible light, infrared light, radar waves, microwaves, radio waves
Vary in energyIonizing vs non-ionizingBelieved to move through space as both a
particle (photon) and a wave (next slide)
Fundamentals of Radiology Left of Visible Light
Longer wavelengths
Lower frequencies
Right of Visible Light: x-raysShorter wavelengths: resulting from tungsten target
being hit with accelerated e- in a vacuum
Higher frequencies
Fundamental of Radiation Wave Concept
Velocity: speed of a wave = speed of lightWavelength: distance between one crest of
one wave and the crest of the next○ Determines the energy and penetrating power○ Shorter wavelength, higher the energy, more
penetrating (harder) the beamFrequency: # wavelengths that pass a given
point in a certain amt of time
WavelengthDefinition: distance in a periodic wave between 2
points of corresponding phrasesFrequency: # of crests that pass per unit of time
Fundamentals of Radiation
Fundamentals of Radiation
Light: wave or a stream of particles?Age old-debateExhibits characteristics of bothParticle: Isaac NewtonWave: Maxwell’s Theory of
ElectromagnetismDescribes wave-like properties of all
electromagnetic radiation
Electromagnetic RadiationProperties expressed best by:
1. Wave Theory
2. Quantum Theory
Fundamentals of Radiation
Electromagnetic RadiationWave Theory
○ How radiation propagated in the form of waves○ Useful when considering radiation in bulk when
millions of quanta are being examined
Electric & magnetic fields orientated in planes at right angles to one anotherOscillate perpendicular to the direction of motion
Fundamentals of Radiation
Electromagnetic Radiation Quantum Theory
○ Electromagnetic energy described as bundles of energy called photons
○ Successful in correlating experimental data Interaction of radiation with atomsPhotoelectric effect Production of x-rays
Fundamentals of Radiation
Fundamental of Radiation Ionization
Most atoms are neutral○ # protons = # electrons
Ion: atom gains or loses an electronAtoms loses an electron, an ion pair results
○ Proton = (+)○ Electron= (-)
Ionizing Radiation: radiation that is capable of producing ions
Fundamentals of Radiation
Photon Elementary particle responsible for electromagnetic
phenomenaCarrier of electromagnetic radiation of all
wavelengths (gamma, x-ray, UV, visible, infrared, microwave, radio)
Differs from electron & quark in that it has zero rest mass
Travels in a vacuum & at the speed of lightHas both wave and particle properties
Fundamental of Radiation Primary Radiation
X-ray beam that exists the tubehead Secondary Radiation
X-radiation that is created when the primary beam interacts w/matter
Scatter RadiationForm of secondary radiationX-ray that has been deflected from its path by the
interaction w/matter Interaction of X-Radiation
X-ray can pass through the patientX-ray can be completely absorbed by patientX-ray can be scatteredX-ray can be transmitted
Light can have 4 fates when hits tissue 1. Absorbed
Primary & beneficial effect of laser energy 2. Reflected
Beam redirecting itself off the surface, no effect on tissueEx: Caries-detecting laser
3. Scattered May harm surrounding structures
4. Transmitted May harm surrounding structuresLaser energy directly through tissues
Fundamental of Radiation Bremsstrahlung Radiation
Produced by sudden slowing or speeding of e- towards a target
Primary source of x-raysNegatively charged e- directed towards a (+)
charged source → loss of velocity occursGenerate continuous spectrum of photons
Characteristic RadiationOnly a minor source of radiation e- from filament displaces an e- from a shell of
tungsten target atom – atom ionizes
NBQ
A radiograph produced from the movement of an electron from an outer shell to a vacancy in an inner shell is referred to as:
a. Thomson scatter
b. Bremsstrahlung radiation
c. Characteristic radiation
d. Particulate radiation
NBQ
A radiograph produced from the movement of an electron from an outer shell to a vacancy in an inner shell is referred to as:
a. Thomson scatter
b. Bremsstrahlung radiation
c. Characteristic radiation
d. Particulate radiation
Properties of X-Rays Characteristics: invisible, no mass, no weight Travel: in a straight line, at the speed of light Wavelengths
Have shorter wavelengths, high frequencyHard x-rays: short, high penetrationSoft x-rays: longer less penetrating, more likely to be
absorbed into the tissues Penetration: pass through matter or absorbed by
matter, depending on atomic structure of matter Produces: an image on photographic film Causes: ionization Distance: lose intensity with distance
Image Characteristics
Detail/Resolution/DefinitionOver sharpness of imageCalled “radiographic definition”Relates to distinct and sharp demarcation of image
elementsFocal spot size: smaller = sharper imageFilm composition: smaller silver halide crystals= sharper
imageMovement of film or patient during exposure= less sharp
imageInfluenced by: BID length, type of films, use of intensifying
screens
Image CharacteristicsPenumbra (“fuzziness or un-sharpness”)
1. Source of radiation small• Small focal spot keep penumbra small• Lg focal spot ↑ penumbra
2. Source to object distance • Long SFD will ↓ penumbra, short SFD will ↑ penumbra
3. Object to film distance • Small object to film distance ↓ penumbra• ↑ source-to-film-distance will ↑ un-sharpness
4. Object and film parallel• Foreshorten or elongation
5. Source perpendicular to object and film
Image Characteristics
Sharpest image w/ least magnification1. Small focal spot
2. Short object-to-film-distance
3. Large target (source)-to-film-distance
4. Film and tooth parallel
5. Beam perpendicular to film
Image Characteristics
DensityOverall Darkness or LightnessMore photons = more densityInfluenced by: film type, processing, exposure
time. mA settings, BID length, kVp setting, source to object distance
ContrastVariations of gray and between white and blackHow sharply dark and light areas are separatedInfluenced by: patient size, film type, processing,
film storage, MAINLY kVp setting
Image Characteristics High contrast/Short Scale
Few shades of gray, mostly black and whitesHigh visual contrastProduced by low kVp settingsLess than 75kVp
Low contrast / Long ScaleMany shades of grayLow visual contrastProduced by high kVpSettings higher than 80kVp
Factors Tubehead Film Density Film Contrast
mA ↑ # photons ↑ density
Exposure Time ↑ # photons ↑ density
kVp ↑ # photons↑ penetration
↑ density Long scale, many grays, low visual contrast
Aluminum ↓ #photonsRemove weak photons
↓ density Long scale, many grays, low visual contrast
Distance Increase
↓ # photons ↓ density
Image Characteristics
RadiolucentPortion of a processed radiograph that is
dark or blackThings that permit the passage of x-raysAir space, soft tissue
RadiopaquePortion of a processed radiograph that is
light or whiteStructures that absorb x-raysEnamel, dentin, bone, metals
Image Characteristics
MagnificationImage appears larger than the actual size of
the object it representsDecrease object-film distance decrease
magnification (tooth close to film)Increase target-to-film distance decrease
magnification (use a longer PID or cone)
Image Characteristics Distortion
Variation in the true size and shape of the object being radiographed
May be unequal magnification of different parts of the same object
Results from improper film alignment or angulation of the x-ray beam
To minimize distortion:○ Object and film must be parallel○ X-ray beam must be directed perpendicular to the
tooth and filmCan cause: Elongation & Foreshortening
Image CharacteristicsPrinciples of Shadow Casting
Geometric Characteristics
Influencing Factors Effect of Influencing Factors
Result
Sharpness Focal spot sizeFilm compositionMovement
↓ focal spot↓ crystal size↓ movement
↑ sharpness↑ sharpness↑ sharpness
Magnification Target-film distanceObject-film distance
↑ target-film dist.↓ object-film dist.
↓ magnification↓ magnification
Distortion Object-film alignment
X-ray beam alignment
Object & film parallelBeam perpend. To object & film
↓ distortion
↓ distortion
DEFINITIONS Attenuation: process where radiation loses power as it travels
through matter. (Removal of x-ray photons) As the energy of radiation ↑, the # of photons passing through
matter ↑ As density, atomic #, electrons per gram of the material ↑, the # of
photons passing through the matter ↓ Elongation
Central ray not perpendicular to object Object and film not parallel Insufficient vertical angulation
Foreshortening Central ray not perpendicular to films Object and film not parallel Excessive vertical angulation
NBQ
Both milliampere and exposure time determine the
a. Degree of film fog
b. Number of x-rays produced
c. Energy of the radiation produced
d. Amount of scattered radiation produced
NBQ
Both milliampere and exposure time determine the
a. Degree of film fog
b. Number of x-rays produced
c. Energy of the radiation produced
d. Amount of scattered radiation produced
NBQ
Which of the following describes a radiographic film that has many graduations of gray from totally white to totally black?
a. Overexposed
b. Underexposed
c. Low contrast
d. High contrast
NBQ
Which of the following describes a radiographic film that has many graduations of gray from totally white to totally black?
a. Overexposed
b. Underexposed
c. Low contrast
d. High contrast
NBQ
Sharpness of the radiographic image is increased by
a. Using a smaller focal spot
b. Decreasing the focal spot-object distance
c. Decreasing the mA
d. Increasing the object-film distance
e. Using screen-film technique
NBQ
Sharpness of the radiographic image is increased by
a. Using a smaller focal spot
b. Decreasing the focal spot-object distance
c. Decreasing the mA
d. Increasing the object-film distance
e. Using screen-film technique
X-RAY MACHINE Glass vacuum tube
All air removedSurrounds electrodes of x-ray tube to provide a
vacuumThe aperture or window: thin segment of the glass
that allows maximum emission of x-rays and minimum absorption by the glass
Leaded glass housingPrevents x-rays from going in all directions
X-RAY MACHINECathode (-)
Serves as the source of e- to be directed at anodeComposed of:
○ Filament (tungsten wire): Filament that lies in a focusing cup: heated to give off e- (thermionic emission)
○ Focusing cup: e- from focusing cup are directed to focal spot
○ mA control regulates
1. Step-down transformer
2. Heating of the filament
3. Quantity of electrons “boiled off” during thermionic emission
○ Because charges repel – the electron beam is directed to a small area on the anode
X-RAY MACHINE
Anode (+)Composed of:
○ Tungsten target (high atomic #) in a ○ Copper stem (remember tungsten & copper) that
functions to conduct heat away from the target○ Focal spot: portion of a target bombarded by electrons
Convert e- from filament into photonsKilovoltage control regulates the:
○ Step-up transformer○ Voltage between the cathode and the anode○ Accelerating potential (speed) of electrons
X-RAY MACHINE
Focal Spot Sharpness of radiograph ↑as size of radiation
source ↓Heat ↑ as focal spot ↓in size
Power SupplyOhm’s Law: Volts = Amperes (I) x Resistance(R)
(electrical potential) (rate of e- flow)
Voltage = kVp. Describes the potential differences between the (-) and (+) and therefore, the speed or force of the moving e-toward the (+) charge
XRAY MACHINEPower Supply: Transformer (changes potential difference of incoming electrical energy to any desired level)
1. Provide low-Volt current to heat filament by use of step-down transformer Operation regulated by mA switch: adjusts R and
therefore current flow – regulates temp. of filament – Quality of x-rays
2. Step-up transformer Increases the voltage sufficiently to propel
electrons across the vacuum tube circuit to produce x-ray energy
3. Generate high difference between anode/cathode Controlled by kVp dial - selects varying V – controls
V between anode & cathode ↑ V = ↑ speed e- toward anode
X-RAY MACHINE
PID: Position-indicating devise○ An open ended, circular or rectangular “cone” that
extends from the tube head toward the image receptor
○ Fed regs: 7cm/2.75in diameter○ Length that ↑ focal-to-object distance creates a less
divergent beam○ Use fastest image receptor system: “F” speed
intraoral film requires the least amt of radiation to produce a diagnostic image
○ Longer PID = produce x-ray beam that is less divergentDecrease radiation exposureProvide better image resolution
NBQ
Federal guidelines limit the size of the intraoral x-ray beam at the client’s skin to:
a. 1 ¾ inches
b. 2 ½ inches
c. 2 ¾ inches
d. 3 ½ inches
e. 3 ¾ inches
NBQ
Federal guidelines limit the size of the intraoral x-ray beam at the client’s skin to:
a. 1 ¾ inches
b. 2 ½ inches
c. 2 ¾ inches
d. 3 ½ inches
e. 3 ¾ inches
NBQ
Which of the following position-indicating devises (cones) best minimizes the dose of radiation to the patient?
a. Pointed, plastic
b. Leaded, circular
c. Leaded, circular
d. Open-ended circular
e. Leaded, rectangular
NBQ
Which of the following position-indicating devises (cones) best minimizes the dose of radiation to the patient?
a. Pointed, plastic
b. Leaded, circular
c. Leaded, circular
d. Open-ended circular
e. Leaded, rectangular
NBQ
Use of which of the following causes unnecessary secondary radiation to the patient?
a. Speed D films
b. Plastic pointed cone
c. kVp under 70
d. Aluminum filtration over 2.0mm
e. Short (8”) target-to-films distance
NBQ
Use of which of the following causes unnecessary secondary radiation to the patient?
a. Speed D films
b. Plastic pointed cone
c. kVp under 70
d. Aluminum filtration over 2.0mm
e. Short (8”) target-to-films distance
FACTORS CONTROLLING XRAY BEAM
Exposure Time Tube Current (mA) Tube Voltage (kVp) Filtration Collimation
X-Ray Beam Quality
Exposure time: duration of x-ray production (quantity)
Distance: greater the distance, less x-ray reach film (quantity)
mA: regulates # e- and thus amt of x-ray produced (quantity)
kVp: regulates the energy or penetrating characteristics of the beam (quality)
X-Ray Beam Quality
Kilovoltage Peak (kVp, Voltage)Voltage is the difference between 2
electrical charges (cathode/anode)This difference determines the speed of e-
when traveling from cathode to the anode65-100 kVpDetermine the quality of x-ray production
(penetrating power)
X-Ray Beam Quantity Exposure Time
Interval of time x-rays are producedLonger exposure = more x-ray photonsLonger exposure = higher density60 impulses/second
mAThe ampere if the unit of quality of electric currentRegulates # e- travelling from cathode to anodeIncreased mA=more x-ray photonsIncreased mA=higher density
X-Ray Beam Quantity
Millampere-seconds (mAs)Both mA & exposure time have a direct
influence on # e- producesWhen combined, they form a factor termed
milliampere-secondsmAs = mA x exposure time (sec)
DistanceGreater distance from source of radiation (x-
ray tube) to x-ray film need more x-ray photons
X-Ray Beam Quantity
Inverse Square LawIntensity of radiation is inversely proportional
to the square of the distance from the source of radiation
Original intensity = New intensity____
New distance 2 = Original distance2
X-RAY MACHINE
FiltrationProcess of selectively removing x-rays from the
beamFilters low-energy, non-penetrating raysFederal regs:
○ 1.5mm of aluminum-equivalent filtration for units operating below 70kVp
○ 2.5mm for units operating above 70kVp
X-RAY MACHINE
CollimationProcess of restricting the size and shape of x-ray
beamAchieved by use of lead diaphragm disc w/ circular
or rectangular opening through which the beam is narrowed
Reduced scatter radiationReduce film fogging
NBQ
The focusing cup in an x-ray tube serves
a. To focus the electron beam
b. As the source of x-rays
c. As the source of electron
d. To focus the x-ray beam
e. Adjust the focal spot
NBQ
The focusing cup in an x-ray tube serves
a. To focus the electron beam
b. As the source of x-rays
c. As the source of electron
d. To focus the x-ray beam
e. Adjust the focal spot
XRAYS & BIOLOGY
X-ray photons are either 1. Absorbed: photons transfer energy to
patient
2. Scattered: photons change in direction
3. Transmitted: photons pass through pt unchanged
Dental x-rays cause 1. Coherent Scattering
2. Photoelectric Absorption
3. Compton Scattering
XRAYS & BIOLOGY
Review interactions of x-rays on humansEffects on oral tissuesEffects on FetusEffects on Total Body: Leukemia, Cancers,
Growth and Development, Gene MutationOsteoradionecrosis
Mandible Bone is destroyed (bone death) Brittleness
XRAYS & BIOLOGY
Radiation InjuryNot all x-rays reach the filmMany are absorbed by patient tissues
IonizationOccurs when x-rays strike patient tissuesMay have little effect on cells if the chemical
changes do not alter sensitive moleculesMay have a profound effect on structures of
great importance to cell function (DNA)
XRAYS & BIOLOGY Free radical formation
A molecule with a single, unpaired e- in its outermost shell
Results with reactive & unstable free radicalsThe ionization of water is the most common
mechanism of damage in humansFR – combine to form- toxins such as H2O2
Dose-response curve & radiation injuryWhat level of radiation is acceptable?No safe amt of radiation exposureDose-response curveCorrelates the damage (response) of tissues w/ amt
(dose) of radiation
XRAYS & BIOLOGY
Sources of radiation exposureNatural radiation
○ Background or environmental radiation○ Cosmetic, terrestrial, radon
Artificial radiation ○ Man-made○ Medical / dental, wristwatches, TV, smoke
alarms, airport security
XRAYS & BIOLOGY Radiographs during pregnancy
ER tx can be done anytime: prefer to avoid 1st trimester2nd trimester bestGenetic dose w/out lead apron
○ Men: 1/10,000○ Women: 1/50,000
Dental vs Background RadiationFMX = 2-4 days4BWX=8 hrsPanoramic = 8 hrs
XRAYS & BIOLOGY
Radiation injury sequence, repair, accumulation1. Latent period: time from exposure to radiation
and appearance of clinical signs
2. Period of injury
3. Recovery period: cellular damage can repair to a certain extent
4. Cumulative effects: effects of radiation exposure are additive
XRAYS & BIOLOGY
Somatic & Genetic EffectsSomatic cells
○ Cells in the body except the reproductive cells○ If effected produce poor health (cataracts,
cancer, etc..) but not transmitted to future generations
Genetic cells○ Reproductive cells (ova, sperm)○ Effects not seen in the person irradiated, but
are passed to future generations
XRAYS & BIOLOGY
Radiation effects on cellsCells may be resistant to radiationCells may be sensitive to radiationDetermined by:
○ Mitotic activity: cells that divide frequently more sensitive
○ Cell differentiation: immature cells are more sensitive
○ Cell metabolism: cells w/high metabolism are more sensitive
XRAYS & BIOLOGY
High sensitivityReproductive tissue, lymphoid system, bone
marrow, intestines, mucous membranes Medium sensitivity
Fine vasculature, growing cartilage/bone, salivary glands, lungs, kidneys, liver
Low sensitivityNerve tissue, skeletal muscle, heart, optic
lens, mature bone
XRAYS & BIOLOGY
Tissue & Radiation EffectHematopoietic (blood-forming)ReproductiveThyroidSkinEyesLeukemiaMutationsCarcinomaCataracts
NBQ
Arrange the following cells and tissues from MOST SENSITIVE to LEAST SENSITIVE to ionizing radiation
1. Adult bone and nerve
2. Epithelium and muscle
3. Alimentary tract and immature bone
4. Blood-forming cells and reproductive cells
a. 1, 4, 2, 3
b. 4, 1, 2, 3
c. 4, 2, 3, 1
d. 4, 3, 2, 1
NBQ
Arrange the following cells and tissues from MOST SENSITIVE to LEAST SENSITIVE to ionizing radiation
1. Adult bone and nerve
2. Epithelium and muscle
3. Alimentary tract and immature bone
4. Blood-forming cells and reproductive cells
a. 1, 4, 2, 3
b. 4, 1, 2, 3
c. 4, 2, 3, 1
d. 4, 3, 2, 1
XRAYS & BIOLOGY Short & Long-Term Effects
Short-term effects○ Assoc w/ large amts radiation○ Nausea, vomiting, diarrhea, hair loss,
hemorrhageLong-term effects
○ Small amts radiation over long period○ Cancer, birth abnormalities, genetic
defects
XRAYS & BIOLOGY Oral effects of radiation
Short-term effects○ Erythema, mucositis○ Ulcers, dermatitis
Long-term effects○ Loss of taste, xerostomia○ Radiation caries, candidiasis○ Possible development of osteoradionecrosis
RADIATION PROTECTION
16in Target-to-film distance 16cm Source-2-skin distance 2.75in Collimation (beam on pt’s
face) Max Permissible Dose (MPD)
Occupational and non-occupational radiation exposure
Old units and new – learn both! (next slide)
RADIATION PROTECTIONMeasurement Old Units S.I. Units
Exposure to air Roentgen Coulomb/Kg
Absorbed dose Rad Gray (Gr)
Dose equivalent in man Rem Sievert (Sv)
Old MPD Occupational 5 rem/yr400 mrem/mo100 mrem/wk
Old MPD Non-Occupational 0.5rem/yr
New MPD Occupational 6.2 Sv/yrNew MPD Non-Occupational 0.005 Sv/yr
RADIATION PROTECTION Filtration
Aluminum discsFilter out long wavelength, low energy x-rays, low
penetrating x-raysTotal filtration > 70kVp = 2.5mm of AluminumTotal filtration ≤ 70kVp = 1.5mm of Aluminum
CollimationRestricts the size and shape of beamLead plate w/ central holeRound or rectangularFederal regulations: x-ray beam < 2.75in @ skin
Position Indicating Devise8in (short)16in (long) < volume of tissue is irritated < scatter
RADIATION PROTECTION Thyroid collar Lead apron
Absorbs 90% of the scatter radiation that would have reached the reproduction tissues
Lead equivalent = 0.25mm Fast film
Film speed determines how much radiation and how much exposure time are necessary to produce an image on a film
Using a fast film is the most effective method to reduce radiation exposure
RADIATION PROTECTION
Films speedDetermines how much radiation and how
much exposure time are necessary to produce a image on a film
A speed (slowest) – F speed (fastest)Speed doubles w/ each letter
○ B twice as fast as A○ C 4x as fast as A
NBQ
With all other technique factors remaining constant, an increase in film speed will:
a. Increase image density
b. Decrease image density
c. Increase image contrast
d. Decrease image contrast
e. Have no effects on the image
NBQ
With all other technique factors remaining constant, an increase in film speed will:
a. Increase image density
b. Decrease image density
c. Increase image contrast
d. Decrease image contrast
e. Have no effects on the image
NBQ
Using an “E” speed group film rather than a “D” speed group film to produce a radiograph requires
a. A longer exposure time
b. A shorted exposure time
c. A decreased developing time
d. An increased developing time
NBQ
Using an “E” speed group film rather than a “D” speed group film to produce a radiograph requires
a. A longer exposure time
b. A shorted exposure time
c. A decreased developing time
d. An increased developing time
NBQ
Using an “E” speed group film rather than a “D” speed group film to produce a radiograph requires
a. A longer exposure time
b. A shorted exposure time
c. A decreased developing time
d. An increased developing time
RADIATION PROTECTION
Intensifying screensUsed in extraoral radiographyReduce exposure time & amt radiation a
patient receives ALARA
All exposure to radiation must be kept to a minimum
“As low as reasonably achievable”
FILM PROCESSING Film Composition
Film base: flexible piece of plasticAdhesive layer: attaches emulsion to film baseFilm emulsion
○ Gelatin: suspends silver halide crystals○ Silver halide crystals: sensitive to radiation
Protective layer Latent Image Formation
Silver halide crystals absorb x-ray and store the energy
Various amts of stored energyInvisible pattern of stored energy: Latent Image
FILM PROCESSING
Film sizesSize 0: BWX/PA in small childrenSize 1: PA’s adult teeth, BWX in kidsSize 2: PA’s adult teeth, BWX in adultsSize 3: BWX’s only. Longer, narrower than
size 2 (shows all post teeth)Size 4: occlusal films
FILM PROCESSING
Extraoral FilmsPanoramic: shows wide viewCephalometric: shows facial profileIntensifying screens
○ Intensify the effect of x-rays on film○ Less radiation is required
FILM PROCESSING
Manual1. Development
2. Rinsing: removes developer
3. Fixation
4. Washing: removes excess chemicals
5. Drying
FILM PROCESSING Developer
Precipitate all of the silver in those silver halide crystals that contain a latent image speck
Swell and soften the emulsion of the filmHydroquinone & Elon5min at 68°
FixerRemove the undeveloped/unexposed silver halide
crystals from emulsionShrink and re-harden the emulsion of the filmSodium thiosulfate & ammonium thiosulfate10min (2x development time)
FILM PROCESSINGDEVELOPER (reduce) FIXER (clear)
Solvent: H2O (soften film emulsion) Solvent: H2O
Preservative: Na-sulfite (protects from oxidation)
Preservative: Na-sulfite (protects from oxidation)
Reducing agents:Phenidone/Elon (older version is Elon) (bring out gray)Hydroquinone (bring out contract)
Clearing agent:Ammonium triosulfate
Activator: alkaline pH Speeds up reducing process
Acidifier: acetic acid (low pH = 4.5)
Restrainer: Na, K, Br (anti-fog agents) Hardening agent: AlK-sulfate, CrK-sulfate, K alum
FILM PROCESSING
Automatic ProcessingDevelopment: 80° for 1.5minFixation: 1.5minWashed: 30secDried: 30sec
NBQ
Radiographic images that are too dark are the result of all the following EXCEPT:
a. Overdevelopment
b. Film Fog
c. Non-exposure to x-rays
d. Hot temperature of solution
e. Over active chemicals
NBQ
Radiographic images that are too dark are the result of all the following EXCEPT:
a. Overdevelopment
b. Film Fog
c. Non-exposure to x-rays
d. Hot temperature of solution
e. Over active chemicals
NBQWhich of the following are purposes of the fixing solution in processing radiographs?
1. Soften emulsion
2. Harden Emulsion
3. Develop exposed silver halide salts
4. Remove undeveloped silver halide salts
a. 1 and 2
b. 1 and 4
c. 2 and 3
d. 2 and 4
e. 3 and 4
NBQWhich of the following are purposes of the fixing solution in processing radiographs?
1. Soften emulsion
2. Harden Emulsion
3. Develop exposed silver halide salts
4. Remove undeveloped silver halide salts
a. 1 and 2
b. 1 and 4
c. 2 and 3
d. 2 and 4
e. 3 and 4
NBQ
A major difference between automatic and manual processing of radiographs is that automatic processing
a. Is more expensive
b. Provides better quality films
c. Allows more latitude in exposure techniques
d. Requires special solutions at higher temperatures
NBQ
A major difference between automatic and manual processing of radiographs is that automatic processing
a. Is more expensive
b. Provides better quality films
c. Allows more latitude in exposure techniques
d. Requires special solutions at higher temperatures
FILM PROCESSING
DarkroomLight-tightSafelighting
○ Low-wattage bulb○ Safelight filter: removes short wavelengths in
blue-green, permits red-orange light○ Min. of 4 feet from film & working area○ Can still cause film fogging w/long exposure
FILM PROCESSING Underdeveloped
Film appears lightInadequate development time or tempDepleted / contaminated developer solution
OverdevelopedFilm appears darkExcess development time or temperatureConcentrated developer solution
Reticulation of EmulsionFilm appears crackedSudden temp change between the developer solution
and the water bath
FILM PROCESSING
Chemical Contamination ErrorsDeveloper spots
○ Dark spots on film○ Developer solution contacts film before processing
Fixer spots○ White spots on the film○ Fixer solution contact film before processing
Air bubbles○ White spots, air trapped on the film surface after being
placed into processing solutionsYellow-brown stains
○ Exhausted chemicals, insufficient rinsing, incomplete fixation
FILM PROCESSING
Film Handling ErrorsOverlapped films
○ White or black areas on film○ Appearance depends if happens in developer or fixer
Static electricity○ Thin, black branching lines○ Occurs when a packet is opened quickly
Slightly bent film○ Elongated roots○ Film may be bent to accommodate pt’s anatomy, such
as in the area of the ant maxillaSeverely bent film
○ Diagonal black line○ Film bent too severely to accommodate patient
FILM PROCESSING
Film Handling ErrorsFingernail artifact
○ Black crescent-shaped marks○ Emulsion damaged by fingernails
Fingerprint artifact○ Black fingerprint○ Touching film
Scratched film○ White lines on film○ Soft emulsion removed from the film by a sharp
objectRoller marks: dirty rollers
FILM PROCESSING
Lighting ErrorsLight leak
○ Exposed area appears blackFogged film
○ Film appears gray and lacks image detail and contrast
○ Improper safelight, outdated films, improper film storage, contaminated solutions
FILM PROCESSING Operator Errors
Pt not biting all way on block○ Air space seen or lack of apices
Tipped film○ Images are tipped to one side
Cone-cut○ Unexposed area on film○ Central ray not in center of film
Cervical burnout○ May appear as dental caries, radiolucent○ Radiolucent artifact seen in areas of different
densities
TECHNIQUEParalleling Technique
XCP technique (extension cone paralleling)RT-angle techniqueLong-cone techniquePrinciples
○ Film is placed in the mouth parallel to the long axis of the tooth○ Central ray of the x-ray beam directed perpendicular to the film
and long axis of the tooth○ Film holder must be used○ To achieve parallelism the film should be placed away from the
tooth and towards the middle of the oral cavity○ Object-film distance is increased○ To compensate for magnification: target-film distance is
increased
TECHNIQUE
Bisecting TechniqueBisecting-angle technique or short-cone
techniquePrinciples
○ Film is placed along lingual surface○ Tooth & film form an angle
Visualize a plane that bisects this angleCentral ray is directed perpendicular to
this imaginary bisector○ Film holders are optional
TECHNIQUEBisecting Technique: Angulation
1. HorizontalPosition of the tubehead in a side-to-side planeCentral ray directed through the contact areas of the teethIncorrect position results in overlapped contact areas (horz
overlap)
2. VerticalPositioning in the up & down planeForeshortened images: Teeth appear shortened, too much
vert angulationElongated images: teeth appear longer, not enough vert
angulation
TECHNIQUELocalization Techniques
Purpose & Use○ 2-D of 3-D object○ Does not depict B-L relationship○ Used to locate: foreign bodies, impacted teeth, unerupted
teeth, retained roots, root positions, salivary stones, jaw fractures, broken needles & instruments, filling materials
Buccal Object Rule○ 2 films at diff angulations○ 1 w/normal angulation and 2nd changing either vert or horz
angles○ Object seen in 2nd film moves in same direction as the
shift of the PID, the object is positioned to the lingual
TECHNIQUE
Take 2 radiographs at 2 different angles can determine if an object is buccal or lingual to together teeth in the archSLOB Rule: Same lingual, opposite buccalThe lingual object moves in the same direction
as the tubeheadThe buccal object moves in the opposite
direction as the tubehead
TECHNIQUE Exposure Problems
Unexposed film○ Film appears clear
Film exposed to light○ Film appears black
Overexposed film○ Film appears dark
Underexposed film○ Film appears light
NBQ
If the object film distance was too great during exposure, then which of the following technical errors is most likely to appear on a processed radiograph?
a. Cone cut
b. Elongation
c. Magnification
d. Foreshortening
e. Proximal overlapping
NBQ
If the object film distance was too great during exposure, then which of the following technical errors is most likely to appear on a processed radiograph?
a. Cone cut
b. Elongation
c. Magnification
d. Foreshortening
e. Proximal overlapping
NBQ
Another maxillary anterior PA is attempted by the dental hygienist and this time the roots of #7-10 are elongated. How would the hygienist go about correcting this error?
a. Increase vertical angulation
b. Decrease vertical angulation
c. Increase horizontal angulation
d. Decrease horizontal angulation
NBQ
Another maxillary anterior PA is attempted by the dental hygienist and this time the roots of #7-10 are elongated. How would the hygienist go about correcting this error?
a. Increase vertical angulation
b. Decrease vertical angulation
c. Increase horizontal angulation
d. Decrease horizontal angulation
TECHNIQUE
Technique Errors: PA’sIncorrect film placementAbsence of apical structuresDropped film cornerAngulation problemsIncorrect horz angulationIncorrect vert angulationCone cut
TECHNIQUE
Technique Errors: BWX’sIncorrect film placementIncorrect horz angulation (horz overlap)Incorrect vert angulationCone cut
TECHNIQUE
Miscellaneous ErrorsFilm bendingFilm creasingIncorrect positioning of pt’s fingerDouble exposureMovementReversed films
Panoramic Basic Concepts
Shows a wide view of the upper and lower jaws on a single film
Extraoral: film is positioned outside the bodyBoth film & tubehead rotate around the patient
Purpose & UseEval impacted teethEval eruption patters, growth, developmentDetect diseases, lesions, conditions of the jawsEval extent of large lesionsEval trauma
Panoramic
FundamentalsTomography
○ Tomo = section○ Radiographic technique that allows the
imaging of one layer or section of the body while blurring images from structures in other places
Focal trough○ Image is clearest
Panoramic
ProsField sizeSimplicityPatient cooperationMinimal exposure
ConsImage qualityFocal trough limitationsDistortionEquipment cost
Panoramic
Patient positioningStraight vertebral columnEnd-to-end tooth position (bite block)Midsagital plane: imaginary line that divides
face into LF-RT, perpendicular to floorFrankfort plane: imaginary plane that passes
the top of the ear canal and the bottom of the eye socket, parallel to the floor
Tongue to roof of mouth
Panoramic
Ghost ImageRadiopaque artifact seen on a pano filmProduced when a radiodense object is
penetrated twice by the x-ray beamSeen on opposite side of the filmIndistinct, larger and higher image
Panoramic
Common ErrorsTongue & Lip Positioning
○ Lips should be closed: dark shadow obscures ant teeth
○ Tongue against palate: dark shadow obscures the apices of maxillary teeth
Panoramic
Common ErrorsFrankfort Plane
○ Chin too high: reverse smile line, downward curve, max incisors blurred, condyles off to side of image
○ Chin too low: exaggerated smile line or jack-o-lantern, curved upward, mand incisors blurred, condyles may not be visible, condyles off top of image
Panoramic
Common ErrorsPositioning of Teeth
○ Too far anterior: ant teeth skinny / out of focus○ Too far posterior: ant teeth fat / out of focus
Midsagital Plane○ Head not centered left-to-right○ Teeth unequally magnified○ One side (side closest to film) smaller○ Other side (side farthest from film) larger
Positioning of Spine○ Pt’s spine must be straight: radiopacity in center of
film
RADIOGRAPHIC INTERPRETATION Definition: types of bone
Cortical (compact) bone○ Sense outer layer of bone○ Radiopaque
Cancellous○ Soft spongy inner bone○ Composed of trabeculae that forms a lattice-
like network of inter-communicating spaces filled w/ bone marrow
RADIOGRAPHIC INTERPRETATION
Definitions: prominencesProcess: marked prominence or projectionRidge: linear prominence or projection of
boneSpine: sharp, thorn-like projection of boneTubercle: small bump or nodule of boneTuberosity: rounded prominence of bone
RADIOGRAPHIC INTERPRETATION
Definitions: depressionsCanal: tube-like passageway through bone
that contains nerves and blood vesselsForamen: opening or hole in bone that
permits the passage of nerves and blood vessels
Fossa: broad, shallow, scooped-out or depressed area of bone
Sinus: hollow space, cavity or recess in bone
RADIOGRAPHIC INTERPRETATION
MiscSeptum: boney wall or partition that divides
2 spaces or cavities, radiopaqueSuture: immoveable joint that represents a
line of union between adjoining bones of the skull, thin radiolucent line
LANDMARKS: MAXILLAIncisive foramen (nasopalatine)
Median palatal suture
Nasal cavity (fossa)
Canine fossa
Nasal septum
Floor of nasal cavity
Anterior nasal spine
Inferior nasal conchae
Maxillary sinus and floor max sinus
Maxillary tuberosity
Hamulus
Zygomatic process maxilla
Zygoma
LANDMARKS: MANDIBLE
Genial tubercles
Nutrient canals
Mental ridge
Mental fossa
Mental foramen
Mylohyoid ridge
Mandibular canal
Internal oblique ridge
External oblique ridge
Submandibular fossa
Coronoid process
LANDMARKS: PANO MAXILLAMastoid process of temporal bone
Styloid process
External auditory meatus
Glenoid fossa (mand fossa)
Articular eminence (tubercle)
Max tuberosity
Infraorbital foramen
Orbit
Incisive canal and foramen
Anterior nasal spine
Nasal cavity, septum
Hard palate
Max sinus
Zygomatic process of maxilla
Zygoma
Hamulus
LANDMARKS: PANO MANDIBLE
Mandibular condyle
Coronoid notch
Coronoid process
Mandibular foramen
Lingula
Mandibular canal
Mental foramen
Hyoid bone
Mental ridge
Mental fossa
Genial tubercle
Inferior border mandible
Mylohyoid ridge
Internal/External Oblique Ridge
Angle of mandible
LANDMARKS: PANO AIR SPACES
Palatoglossal air space
Nasopharyngeal air space
Glossopharyngeal air space
1. Lingual Foramen2. Genial tubercles3. 3-unit bridge4. Palate5. Mandibular Canal6. Mental Foramen7. Maxillary Sinus8. Coronoid process9. Third molar10.Mastoid air cells11.Articular eminence12.Pterygomaxillary fissures13.Lateral pterygoid plate14.Orbital floor
ANSWERS
1. Mandibular Foramen2. Styloid Ligament3. Palate4. Nasal fossa5. Hyoid bone6. Air space7. External oblique ridge8. Internal oblique ridge9. 3-unit bridge10.Angle of mandible11.Ramus12.Condyle13.Mandibular notch14.Coronoid process15.Retention ortho wire
ANSWERS
1. Anterior Nasal Spine2. Nasal Fossa3. #13 root canal & crown4. #14 with root canal &
crown5. #2 with crown6. Max sinus7. Trabeculae8. Zygomatic process of
maxilla9. Nasopalatine Foramen10.Median palatine suture
9
10
2
10
1
3 4
77
65
8 6
7
1. Recent extraction site
2. Implant Abutment3. Molar with root
canal4. Maxillary sinus5. Root apex6. Zygomatic process7. Maxillary tuberosity
#5
6
7
I
1. Possible periapical abscess
2. Lamina dura3. PDL4. Inferior border of
mandible5. Mandibular Canal
1
44
2
3
5
1